[ZJOI2010] base site

TheLostWeak Explain very clearly, it will not create the wheel of

#include <bits/stdc++.h>
#define ll long long 
#define ls (x<<1)
#define rs (x<<1|1)
using namespace std;

const int N=2e4+10;
const int inf=0x3f3f3f3f;

int n,K;
int d[N],c[N],s[N],w[N],f[N];
vector<pair<int,int>> L[N];

int val[N<<2],tag[N<<2];
void psh(int x) {
    if(!tag[x]) return;
    val[ls]+=tag[x],tag[ls]+=tag[x];
    val[rs]+=tag[x],tag[rs]+=tag[x];
    tag[x]=0;
}
void build(int x,int l,int r) {
    tag[x]=0;
    if(l==r) {val[x]=f[l]; return;}
    int mid=(l+r)>>1;
    build(ls,l,mid); 
    build(rs,mid+1,r);
    val[x]=min(val[ls],val[rs]);
}
int query(int x,int l,int r,int L,int R) {
    if(L<=l&&r<=R) return val[x];
    int mid=(l+r)>>1,ret=inf; psh(x);
    if(L<=mid) ret=query(ls,l,mid,L,R);
    if(mid<R) ret=min(ret,query(rs,mid+1,r,L,R));
    return ret;
}
void modify(int x,int l,int r,int L,int R,int w) {
    if(L>R) return;
    if(L<=l&&r<=R) {val[x]+=w; tag[x]+=w; return;}
    int mid=(l+r)>>1; psh(x);
    if(L<=mid) modify(ls,l,mid,L,R,w);
    if(mid<R) modify(rs,mid+1,r,L,R,w);
    val[x]=min(val[ls],val[rs]);
}

int main() {
    scanf("%d%d",&n,&K); 
    for(int i=2; i<=n; ++i) scanf("%d",d+i);
    for(int i=1; i<=n; ++i) scanf("%d",c+i);
    for(int i=1; i<=n; ++i) scanf("%d",s+i);
    for(int i=1; i<=n; ++i) scanf("%d",w+i);
    n++; K++; d[n]=inf; w[n]=inf; 
    for(int i=1; i<=n; ++i) {
        int l=lower_bound(d+1,d+n+1,d[i]-s[i])-d;
        int r=upper_bound(d+1,d+n+1,d[i]+s[i])-d-1;
        L[r].push_back({l,w[i]});
    }
    for(int i=1,sum=0; i<=n; ++i) {
        f[i]=sum+c[i];
        for(auto p:L[i]) sum+=p.second;
    }
    for(int T=2; T<=K; ++T) {
        build(1,1,n); memset(f,inf,sizeof f);
        for(int i=T; i<=n; ++i) {
            for(auto p:L[i-1]) modify(1,1,n,T-1,p.first-1,p.second);
            f[i]=query(1,1,n,1,i)+c[i];
        }
    }
    printf("%d\n",f[n]);
    return 0;
}